The following key points are important for a better understanding of Azure DNS delegation:

• When adding the name servers for delegation, it is recommended to add all the four name servers for higher availability and better resiliency. Also, in order to get Azure DNS SLA applied, you need to make sure that the four name servers are delegated.
• The domain registrar is the company that can provide an internet domain name, such as GoDaddy, Namecheap, Google, and so on.
• NS records are the responsible records for pointing to name servers.